The Anomalous Photo‐Nernst Effect of Massive Dirac Fermions In HfTe5

Abstract The quantum geometric Berry curvature results in an anomalous correction to the band velocity of crystal electrons with a corresponding transverse (thermo)electric conductivity. However, time‐reversal symmetry typically constrains the direct observation and exploitation of anomalous transpo...

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Bibliographic Details
Published in:Advanced Physics Research 2024-03, Vol.3 (3), p.n/a
Main Authors: Maanwinder P. Singh, Jonas Kiemle, Chen Xu, Waldemar Schmunk, Qingxin Dong, Genfu Chen, Tobias Meng, Christoph Kastl
Format: Article
Language:English
Subjects:
anomalous Hall effect
anomalous Nernst effect
berry curvature
photocurrent
topological insulator
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Summary:Abstract The quantum geometric Berry curvature results in an anomalous correction to the band velocity of crystal electrons with a corresponding transverse (thermo)electric conductivity. However, time‐reversal symmetry typically constrains the direct observation and exploitation of anomalous transport to magnetic compounds. Here, it is demonstrated the anomalous Hall and Nernst conductivities are essential for describing the optoelectronic transport in thin films of the non‐magnetic, weakly gapped semimetal HfTe5 subject to an external magnetic field. A focused photoexcitation adresses the symmetries of the local Nernst conductivity, which unveils a hitherto hidden, anomalous photo‐Nernst effect of three‐dimensional (3D) massive Dirac fermions. The experimental temperature and density dependencies are compared with a semiclassical Boltzmann transport model. For HfTe5 thin films with the Fermi level close to the gap, the model suggests that the anomalous photo‐Nernst currents originate from an intrinsic Berry curvature mechanism, where the Zeeman interaction effectively breaks time‐reversal symmetry of the massive Dirac fermions already at moderate external magnetic fields.
ISSN:2751-1200
DOI:10.1002/apxr.202300099